<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    *{
        margin: 0;
        padding: 0;
        list-style-type: none;
    }
    html,body{
        height: 100%;
        overflow: hidden;
    }
    #box1{
        width: 100%;
        height: 100%;
        background: skyblue;
        display: -webkit-box;
        -webkit-box-pack: center;
        -webkit-box-align: center;
    }
</style>
<body>
    <div id="box1"></div>
</body>
</html>